Trim 10 lines. Roger, please revert any of this you disagree with.

svn:r1048
This commit is contained in:
Nick Mathewson 2004-02-01 04:09:15 +00:00
parent 43efb87bbc
commit 20f56091ce

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@ -316,10 +316,10 @@ calls for padding between end users and the head of the
cascade~\cite{web-mix}. However, it is not demonstrated whether the current
implementation's padding policy improves anonymity.
{\bf PipeNet}~\cite{back01, pipenet}, another low-latency design proposed at
about the same time as Onion Routing, provided
stronger anonymity at the cost of allowing a single user to shut
down the network simply by not sending. Systems like {\bf ISDN
{\bf PipeNet}~\cite{back01, pipenet}, another low-latency design proposed
around the same time as Onion Routing, gave
stronger anonymity but allowed a single user to shut
down the network by not sending. Systems like {\bf ISDN
mixes}~\cite{isdn-mixes} were designed for other environments with
different assumptions.
%XXX please can we fix this sentence to something less demeaning
@ -340,15 +340,15 @@ These systems are designed primarily for communication between peers,
although Herbivore users can make external connections by
requesting a peer to serve as a proxy.
Systems like {\bf Freedom} and the original Onion Routing build the circuit
Systems like {\bf Freedom} and the original Onion Routing build circuits
all at once, using a layered ``onion'' of public-key encrypted messages,
each layer of which provides a set of session keys and the address of the
each layer of which provides session keys and the address of the
next server in the circuit. Tor as described herein, Tarzan, MorphMix,
{\bf Cebolla}~\cite{cebolla}, and Rennhard's {\bf Anonymity Network}~\cite{anonnet}
build the circuit
in stages, extending it one hop at a time.
build circuits
in stages, extending them one hop at a time.
Section~\ref{subsubsec:constructing-a-circuit} describes how this
approach makes perfect forward secrecy feasible.
approach enables perfect forward secrecy.
Circuit-based anonymity designs must choose which protocol layer
to anonymize. They may choose to intercept IP packets directly, and
@ -1311,11 +1311,13 @@ itself may be hostile). While filtering content is not a primary goal
of Onion Routing, Tor can directly use Privoxy and related
filtering services to anonymize application data streams.
\emph{Option distinguishability.} We allow clients to choose local
\emph{Option distinguishability.} We allow clients to choose
configuration options. For example, clients concerned about request
linkability should rotate circuits more often than those concerned
about traceability. There is economic incentive to attract users by
allowing this choice; but at the same time, a set of clients who are
about traceability. Allowing choice may attract users with different
%There is economic incentive to attract users by
%allowing this choice;
needs; but clients who are
in the minority may lose more anonymity by appearing distinct than they
gain by optimizing their behavior~\cite{econymics}.
@ -1558,7 +1560,7 @@ all its CPU time in AES, which is fast. Current latency is attributable
to two factors. First, network latency is critical: we are
intentionally bouncing traffic around the world several times. Second,
our end-to-end congestion control algorithm focuses on protecting
volunteer servers from accidental DoS rather than optimizing
volunteer servers from accidental DoS rather than on optimizing
performance. % Right now the first $500 \times 500\mbox{B}=250\mbox{KB}$
%of the stream arrives
%quickly, and after that throughput depends on the rate that \emph{relay
@ -1819,8 +1821,10 @@ our overall usability.
In this appendix we provide more specifics about the rendezvous points
of Section~\ref{subsec:rendezvous}. We also describe integration
issues, related work, and how well the rendezvous point design
withstands various attacks.
issues and related work.
%, and how well the rendezvous point design
%withstands various attacks.
% (Not any more; it's currently commented out. -NM)
\SubSection{Rendezvous protocol overview}
@ -1841,9 +1845,9 @@ application integration is described more fully below.
rendezvous cookie to recognize Bob.
\item Alice opens an anonymous stream to one of Bob's introduction
points, and gives it a message (encrypted to Bob's public key)
that tells him
about herself, her chosen RP and the rendezvous cookie, and the
first half of a DH
telling it about herself,
her RP and rendezvous cookie, and the
start of a DH
handshake. The introduction point sends the message to Bob.
\item If Bob wants to talk to Alice, he builds a circuit to Alice's
RP and sends the rendezvous cookie, the second half of the DH
@ -1853,8 +1857,8 @@ application integration is described more fully below.
shares the key only with Bob.
\item The RP connects Alice's circuit to Bob's. Note that RP can't
recognize Alice, Bob, or the data they transmit.
\item Alice now sends a \emph{relay begin} cell along the circuit. It
arrives at Bob's onion proxy. Bob's onion proxy connects to Bob's
\item Alice sends a \emph{relay begin} cell along the circuit. It
arrives at Bob's OP, which connects to Bob's
webserver.
\item An anonymous stream has been established, and Alice and Bob
communicate as normal.
@ -1890,11 +1894,11 @@ introduction connections open or risking such an attack. In this case,
he can provide selected users
with a current list and/or future schedule of introduction points that
are not advertised in the DHT\@. This is most likely to be practical
if there is a relatively stable and large group of introduction points
if there is a stable and large group of introduction points
available. Alternatively, Bob could give secret public keys
to selected users for consulting the DHT\@. All of these approaches
have the advantage of limiting exposure even when
some of the selected high-priority users collude in the DoS\@.
some of the selected users collude in the DoS\@.
\SubSection{Integration with user applications}